A type of printer is known in which inks of various colors are transferred in a sequentially overlaid fashion from an ink ribbon containing, for example, Y (yellow) ink, M (magenta) ink, C (cyan) ink, an OP (overcoat), etc., onto a recording sheet such as photographic paper by using heat generated by a thermal head. The ink ribbon is a belt-like sheet on which inks of different colors are arranged repeatedly in the same order along its longitudinal direction, and is enclosed in a ribbon cassette by being wound on a ribbon supply roller. When printing, the ink ribbon is fed from the ribbon supply roller toward a ribbon take-up roller by driving the ribbon roller to rotate, and while being transported, the ink ribbon passes the thermal head together with the recording sheet. By transporting the ink ribbon and the recording sheet in synchronized fashion, the inks of the respective colors are transferred in sequence for printing on the same area on the recording sheet.
In this type of printer, the rotating shaft of the ribbon roller is connected to a driving unit to drive the ribbon roller to rotate; since the ribbon roller needs to be removed when replacing the ink ribbon, it is desirable that the ribbon roller be easily disengageable from and connectable to the driving unit.
For example, patent document 1 discloses a printer including an ink ribbon accommodating unit for accommodating an ink ribbon in a rotatable and axially slidable fashion, a driving unit, provided in a printer body, for supplying and rewinding the ink ribbon, and a moving mechanism for moving the ink ribbon inside the ink ribbon accommodating unit in an axially sliding fashion. In this printer, the moving mechanism moves the ink ribbon so as to slide along the axial direction inside the ink ribbon accommodating unit and thereby connects the ink ribbon to the driving unit, and the driving unit is driven to supply and rewind the ink ribbon.
On the other hand, patent document 2 discloses a thermal transfer printer including a unit which is mounted on a shaft so as to straddle a door frame and so as to be slidable along an extending direction of the shaft, and which can be engaged with and disengaged from an ink bobbin by being moved slidably along the shaft and, when engaged, can drive the ink bobbin to rotate, and a pressing member which is provided on a cabinet so as to be able to contact the unit when the door frame is moved from a first position to a second position. In this printer, the unit is engaged with and disengaged from the ink bobbin as the pressing member is brought into contact with and separated from the unit.